As a sommelier and brewer, I can provide you with a detailed explanation of the difference between a carboy and a demijohn. These terms are often used interchangeably, but there are some subtle distinctions based on regional usage and volume.
1. Carboy: In most cases, when people refer to a carboy, they are talking about a 5 US gallon (19 L) glass container. The term “carboy” itself is commonly associated with this specific size. Carboys are commonly used in homebrewing and winemaking due to their convenient size for fermentation and aging. They are made of glass or plastic and have a narrow neck, allowing for the attachment of airlocks and other accessories. Carboys are versatile vessels that can be easily cleaned and sanitized, making them popular among brewers and winemakers.
2. Demijohn: On the other hand, the term “demijohn” is used to describe a larger glass container, typically holding 15 US gallons (57 L) of liquid. In some regions, such as the Philippines, a 15-gallon demijohn is known as a “dama juana.” In the United Kingdom, a “demijohn” refers to a 1-imperial-gallon (4.5 L) glass brewing vessel. Demijohns have a wider body and are often used for bulk storage or aging of wine, cider, or other fermented beverages. The larger size allows for longer aging periods and larger batches.
3. Regional Variations: It's worth noting that the usage of these terms can vary by region. In some areas, the term “carboy” might refer to any size of glass container, while in others, it may specifically indicate a 5-gallon vessel. Similarly, the term “demijohn” may refer to various sizes depending on the country or even the specific context within the brewing or winemaking community.
The main difference between a carboy and a demijohn lies in their volume capacity. A carboy is typically a 5-gallon vessel, while a demijohn is larger, often holding 15 gallons or more. The specific usage and terminology can vary based on regional preferences and brewing traditions. Both carboys and demijohns are commonly used in the fermentation and aging processes of brewing and winemaking, providing brewers and vintners with versatile vessels for their craft.